Ross Barkley is absent from Everton's squad for a pre-season trip to manager Ronald Koeman's homeland of Netherlands as well as Belgium.
The Premier League club said Barkley - who also did not travel to Tanzania to play Kenyan side Gor Mahia - has stayed behind to continue his recovery from a groin injury, but transfer speculation involving the player is likely to intensify as a result.
Barkley has a year remaining on his Everton contract and Koeman has regularly said the midfielder will be sold unless he is willing to commit to an extended deal.
The England international, who scored five goals in his 36 Premier League appearances last season, has long been linked with a move to Tottenham, but Everton are reported to be demanding £50million for the 23-year-old.
New signings Wayne Rooney, Jordan Pickford, Michael Keane, Sandro Ramirez, Davy Klaassen and Cuco Martina - whose arrival from Southampton was confirmed on Monday - are all in the club's tour squad.
Everton are due to face FC Twente on Wednesday before travelling to Belgium, where they will play Genk on Saturday.